The barrel of the Regulation Police has the typical Smith rollmark of the period. Traditional sans serif font and "lazy" ampersand.
The markings on the barrel of the paltik don't resemble any alphabet I can find, and may be "greeking". There's a fascinating...and fairly recent...piece on the underground gun industry in Cebu here at the NYT. (It may be paywalled. I trust you're savvy enough to find your way around that via an archive if necessary.)
If dudes in the jungle in the 1920s or 1930s could do this, probably with hand tools, imagine what could be done in a CNC-equipped home workshop in 21st Century America.
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